Day seven was the last full day we would spend in Paris.
I had one serious objective for the day: Notre Dame.
We'd walked past it the first day, but the rest of the group wanted to pass by the tourists and see other sights. I went back with Dushyanth this day, and I'm glad I did. As before, it was infested with tourists (an aside: you typically hear about how obnoxious and boisterous American tourists are, but I really didn't see any while I was in Paris -- at least, not any being particularly obnoxious. However, the German tourists were plenty loud and... active, so take from that what you will.)
The interior of Notre Dame is gorgeous, but the real treat is to go up the stairs to wander around where the gargoyles are. As with the Arc de Triomphe, there were a huge number of steps to ascend, but they were well worth it. (Also, you have to pay to see the top, whereas the main floor is free.)